Abstract

In previous work,⁽¹⁾ it has been shown that the magnitude of the OH absorption at 1.38 µm in silica fibers can be reduced by an OH → OD exchange process. In post-treated fibers a reduction exceeding a factor of 150 has been demonstrated. In this work we show a reduction in the OH absorption in a MCVD-made fiber by treating only the substrate tube used to fabricate the preform. The Heraus waveguide quality T08 tubing, 16 mm o.d., 13 mm i.d., was treated at 1000°C in a. D₂ atmosphere for 20 hours (See Fig. 1). In this process the OH in the tube was converted to OD,⁽²⁾ and in addition, D₂ gas was dissolved in the silica with a concentration estimated⁽³⁾to be 10¹⁷ molecules/cm³.

© 1981 Optical Society of America